Motor



April 8, 1941. c. A. NEWMAN MOTOR Filed Dec. 7', 1938 a mmmm:

wa namr UNITED; STATES -PATENT OFFICE suma- IorronCariLNewmanJocheatenNJu amasmu 1; me, an 244,41:

' scum (cute-m This invention relates to a dental implement, admirablyadapted ioruse as arotary tooth brushereasanumberoideviceloithisclasshavebeenpatentedoveraperiodotmanyyeammost of them have beenimpracticai'because of involved gearing, complex clutches and chucks, ortheyhavebeengeneraliybulkmmadeoimany separate parts and inherentlyexpensive. The present invention proposes to provide an implementoi'this type with few parts, whichis simple in comtruction. inexpensive,and safe to use'wlthout danger otshock tothe user or penetrationotfioreign matter to the operating mech- A housing I. composed ofnon-conducting material such as hard rubber or synthetic resins isprovided with an enlarged end it of substantially uniform sectionserving as a handle for the device and receiving a motor II. A reducedend N or substantially uniform section is made integral with theenlarged portion through an intermediate convergent portion ii. Anon-conductive cap ii is suitably titted .to the enlarged end 0! thehousing as by screw threading or the like to enclom the operating parts.As shown, the cap II is provided with a switch handle 20, rotatablyassembled thereon, for controlling the I circuit used in driving themotor. The housing, can and switch handle may be molded from plastics ofthe type contemplated, in accordance with tool such as a toothbrush.Anon-conductive cap.is'provided forclosingtheenlargedendoi"thehousingand supported mbearingsprovidedintheeapandlorintheanathema-nudism; v hmoreecmplcteoitheinyenthe present day practice andat a relatively low cost.

The motor l3 consists of a stator 22 Irictionally or otherwise fixed inthe housing, a rotor 24 and a commutator It." Brushes II of theusual'type establish the commutator circuit through connections whichhave been omitted since they constitute no part of the presentinvention. The

brushes are held in position by springs 21 and non-conducting caps 29 ofthe usual type. A shaft 3| projects from the rotor towards the reducedend of the housing and is joined through a non-conductive coupling 32 toashatt extension 34 which projects beyond the reduced end of the housingfor attachment of a tool. The tool depicted diagrammatically in thedrawing is a tooth brush II composed of bristles set in a non-conductivesupport 38. The support may be formed with internal threads ll forcooperation 'with=similar threads on;the end of the rotor shaftextension 34.- The shaft extension may be provided with a squared ornon-circiflarportion 31 adjacent its threaded'end adapted to receive abridging member or guard 38 of non-conductive material having a borecomplementary with the non-circular portion of the shaft. This guard I aor substantially H-shape in section, its oppositely disposed flanges l2and 44 bridging the adjacent ends of the bristle support and housingrespectively. 'Ihe flange covering the bristle ticn willbepccdblenponretereace to the-atof theimplement; and partly in sectiontaken elevation an. 1.

support may engage it trictionally, but the opposite flange willpreferably have a slight clearance with respect to. the reduced end ofthe housing. This guard serves not only to exclude water and otherforeign matter mm the operat-' in! parts within the housing but likewisereduces the danger of shock to the user.

Bearings may be suitably arranged within the cap and/or the housing andas shown, a bearing 46 is mounted in the housing near the junction ofthe converging portion and the reduced end.

by an inwardly directed flange 52 integral with the housing near thejunction of the enlarged end with the convergent portion. Here again apacking 54 saturated with a lubricant may he used.

The opposite end oi the rotor is provided with a shaft extension 56which is moon as received in a bearing 58 carried by the cap 08. Thishear ing may likewise be equipped with a lubricated packing 68.

A switch for controlling the motor circuit is accuses f The scope oi thepresent invention should not be restricted to the details of thespecific examplesset forth in. the foregoing description, hut

should be construed only in accordance with the depicted, by way ofexample as carried by the cap iii and comprises resilient contacts 62and 64, one of which will be fixed to the cop and the other rotatablewith the switch handle 25. Con rent is supplied through a pair ofconductors 65% inserted through an aperture $8 formed in the end of theswitch handle.

It will be clear from the foregoing description that the device may beused in a substantially horizontal position under which conditions theoperator will grasp the enlarged portion of the housing and since thecenter of gravity is sub-- stantially at the mid-point of this portion,a balanced condition will exist.

, that an operator can use the implement by'grip ping the reducedportion or convergent portion of the Housing between his thumb, andforefinger in much the manner a pencil is held, in which.

It will be noted i terms of the appended claims.

I claim:

i. A dental implement comprising a non-con ductive housing having anenlarged end of substantially uniform section providing a handle, areduced and of substantially uniform section integral therewith, and anintermediate convergent portion joining said ends; a rotary electricmotor received within said enlarged end having a rotor shaft extendinginto and projecting beyond said reduced end for attachment of a dentaltool; a non-conductive cap closing the enlarged end of said housing; abearing in said housing for supporting said rotor shaft; ands, non-conductive guard covering the projecting end of said shaft andnon-rotatahly mounted thereon.

2. A dental implement comprising a non-con- .ductive housing having anenlarged end of substantiaily uniform section providing a handle, areduced end of substantially uniform section concentric and integraltherewith, and an intermediate convergent portion .lolning said ends; a

' rotary electric motor received within said en is so designed, that theattached brush or other It will be clear that under all conditions andparticularly when used for brushing the teeth,

larged end having a rotor shaft extending into and projecting beyondsaid reduced end for attachment of a dental tool; a non-conductive capprovided with a non-circular portion; and a nonconductive guard having abore complementary with said non-circular portion of said shaft received thereon. r F

. QARL A. NEWMAN.

